Answers

The fact that this question is based on a FALSE premise is why we have a moron for a president in the first place. Did you actually even read the article?

First of all this agreement has nothing to do with counties "paying" anyone, let alone NATO. This money does go into NATO's coffers. What countries pay to NATO is a different pot of money under a different agreement that is not the topic of this article. The agreement is that that NATO "spend" 2% of their GDP on their own military, by 2024. So far there is no indication that any country will fail to meet this obligation.

Trump is making up a problem that doesn't exist and then claiming to solve it with is mad negotiating skills. In reality the only thing he is doing is threatening the credibility of the United States and making us look like a Putin puppet.

He can't get them to do anything, because he's not a persuasive person. He can only make angry demands, and that's only effective upon people who are either afraid of him or impressed by him. The other NATO countries are neither.